ROSWELL, Ga. - A convicted sex offender is facing charges after police said he groped a woman at a Roswell store, and investigators are crediting quick-thinking witnesses for helping catch the suspect.

"He came in here and was just making rude comments and gestures to people, like sticking his tongue out and grunting and making sexual noises," she said.

Police said Lee's bizarre behavior soon turned criminal when they said he grabbed a woman's buttocks.

"I followed him and took a picture of his license plate so we could hopefully get the police and track him down," said Sullivan.

Sullivan showed Petchenik the pictures, which included images of Lee running out of the store and getting into his pickup truck. Police told Petchenik they were able to track Lee down using the license plate number from the picture.

"We're always encouraging people to be alert, vigilant and get that information for us," said Officer Lisa Holland. "Without a tag number or a great description, it's hard for us to follow up on these cases."

Sullivan said she's thankful police caught up with Lee.

"I'm glad," she said, "I don't want him to do it to other women."

Georgia Department of Corrections records online show Lee was convicted of rape, burglary and aggravated assault in Cobb County in 1988 and spent about 20 years in prison. He was also convicted for failing to register as a sex offender. Lee is currently being held in the Fulton County jail.

"This guy had already spent an excessive amount of time in jail for sexual offenses, and he's back out again. Obviously jail's not the solution," said Sullivan. "Maybe there's some kind of mental help he needs, some kind of institutionalized doctor's care."